Pneumatic striker unit for player pianos



June 17, 1930. w. B. TUNSTALL PNEUMATIC STRIKER UNIT FOR PLAYER PIANOSOriginal Filed July 11, 1927 2 Sheets-Sheet l June 1 7, 1930. w. B.TLJNSTALL 1,765,112

PNEUMATIO S TRIKER UNIT FOR PLAYER PIANOS Original Filed July 11, 19272.Sheets-Sheet 2 Patented June 17, 1930 @FFEQ WILLIAM B. TUNS'IALL, OFWORCESTER, MASSACHUSETTS PNEUMATIC STRIKER UNIT FOR PLAYER PIANOSOriginal application filed Ju1y 11, 1927, Serial No. 204,873. Divided.and this application filed July 9,

structure that is particularly adapted for production in largequantities at low cost.

Each striker unit is a duplicate of the others and the internalconstruction of each unit is such that the width of a unit is so reducedthat a large number can be arranged in a single row extending across thepiano with the unitsin substantial alinement with the corresponding keysof the instrument. Each .unit is further characterized by an improvedarrangement of valves therein whereby when a note is struck by thecollapse of the power pouch, the valve controlling this action opens inthe direction of the induced flow of air thereby resulting in very rapidand positive action of the note striking means.

The above and other advantageous features of my invention willhereinafter more fullyappear, reference being had to the accompanyingdrawings in which Fig. 1 is a View partially in section and partially inend elevation of a portion of an upright piano provided with my improvedstriker units.

Fig. 2 is a view in front elevation of a number of keys with the strikerunits controlling the same.

Fig. 3 is a perspective view of one of my improved striker units removedfrom the piano.

Fig. i is a perspective view of the unit shown in Fig. 3 with the powerpouch removed.

Fig. 5 is a perspective view similar to Fig.

4 looking at the other side of the unit.

Fig. 6 is a sectional view through the unit along the line 6, 6 of Fig.13.

Serial No. 291,312.

Fig. 7 is a sectional view along the line 7, 7 of Fig. 5.

Fig. 8 is a sectional view similar to Fig. 6 showing the striker unit incollapsed condition to strike a note.

Fig. 9 is a fragmentary view showing a portion of Fig. 7 on an enlargedscale.

Like reference characters refer to like parts in the diflerent'figures.

Referring first to Fig. 1, one of my improved striker units is shown inconnect-ion with the usual parts of a player piano and also inconnection with the parts of the improved pneumatic action which formsthe subject matter of my aforesaid original application Serial No.204,878, itbeing obvious that striker units of the present invention maybe as well employed with other types of pneumatic actions. The spool box1 is of any usual construction with a tracker bar 2,

take-up spool 3 and tubes 4 leading from the tracker bar 2 to myimproved striker units, one of which is generally designated by thereference numeral 5. As shown in Fig. 2, the units 5 are of such widththat a single row of them extending across the piano is sumcient toprovide for the playing of all of the notes of the key board which canbe manually operated by keys 6.

As set forth in detail in my original application Serial No. 204,873,the striker units 5 form part of a pneumatic action located entirelyabove the keys 6, the component parts of this action comprising a mainchannel board 7 having a bellows section or chamber 8 and an actionsection or wind chest 9 extending behind the row of striker units 5.Rigidly secured to the channel board 7 and in communication with thebellows chamber 8 are mounted the feeders or eXhausters 10 and thereservoir 11. The movable leaf 10 of each feeder 10 is connected bymeans of a link 12 to any suitable pedal mechanism not shown, suitablevalves 13 and 14 being provided to regulate the fiow of air from thebellows chamber 8 1 0 the reservoir 11.

During the operation of the mechanism, the bellows section 8 is adaptedto be connected to the wind chest 9 by suitable valves not shown and thewind chest 9 provides spaced ducts each adapted to su ply vacuum fromthe wind chest to one of the striker units 5. Eachstriker unit 5provides what will be hereinafter termed a power pneumatic whichconsists of two movable leaves 16 and 17 connected by flexible material18, the outer leaf 16 carrying a striking lever 16 extending in thedirection of the piano action. Normally the pouch is expanded and a noteis adapted to be struck by collapse of the pouch and upward movement ofthe lever 16*, in response to operation of the pneumatic unit which willnow be described in detail with reference to Figs. 3 to 8 inclusive.

As best shown in Fig. 3 each pneumatic unit 5 consists of an L-shapedblock, preferably of wood and fabric, the elongated portion 5 of whichprovides a beveled projection 19 to which the center leaf 17 of thepouch is hinged by means of a piece of fabric 20 attached to the centerleaf 17, the rejection 19 and to the end of the outside ea'f 16respectively. The center leaf 17 provides a passage 17 to the spacebetween the pouch material 18 and the'outer leaf 16, the two leaves 16and 17 in combination giving added power to the action of the unit ascompared to a single leaf pneumatic unit.

A rubber tube 4 leading from the tracker bar 2 is connected to the unitblock 5 by means of a nipple 21 which opens into a longitudinal passage22 rovided in the elongated block portion 5. his channel 22 leads into achamber 23 forming part of an annular recess 23 provided on one face ofthe block 5 and the channel 22 is also in communication with a tube 24received in an opening 25 extendin transverse across the block, seeFigs. and 9. T e tube 24 in passing through the block bridges a slot 26extending verticall downwardly from the to surface of the lock to thecenter thereo ,this slot 26 being in communication with the powerpneumatic as clearly shown in Fig. 6. The tube 24 makes a ti ht fit inthe hole 25 so that there is no possi ility of anyleakage of atmosphericpressure from the tube 24 into the slot 26. V

vThe end of the tube 24 opposite to the tracker bar channel 22 ispartially blocked by, a closure 27 which provides a small vent hole 28so that the channel'22 is in restricted communication with a smallcircular recess 29 provided in the face ofthe block in the form of ashallow bore. 'The'recess 29 is in turn in communication with similarrecesses 29 and 29. both of which open into a deeper recess 30 as bestshown in Fig. 5, it being possible to make all of the recesses by meansof different sized boring tools. The recess a 29" is in communicationwith a slot 31 extend- 7 ing vertically through the rear of the block,

which slot -may be conveniently made by means of a circular saw. Theslot 31 is 65 adapted to register with a duct 15 extending from the windchest 9 as shown in Fig. 1, so that the vent 28 in the tube 24 is indirect communication with the wind chest 9 and the tube 24 is subjectedto a limited amount of vacuum effect.

As previously pointed out, the recesses 29 and 29" are in communicationwith the doc recess 30 and this recess 30 adjoins a sma ler concentricopening 32 located substantially at the center of the block, into whichopening 32 extends the slot 26 from the power pouch previously referredto. A valve spindle 33 is supported within the central opening 32 bymeans of a guide 34 and this spindle 33 carries at op osite ends thereofvalvedisks 35 and 36. Ks shown in Fig. 6 the valve disk 36 is normallyseated in engagement with the shoulder 32" separating the recess 30 fromthe central opening 32, so that the central opening 32 is shut off fromthe suction normally existent within the recess 30.

The other valve disk 35 is carried by a diaphragm 37 which is anchoredaround its periphery to a shoulder 38 provided in the recess 23 by meansof a ring 39. The side of the diaphragm 37 opposite to the valve 35carries a disk 40 which bears a ainst the side wall 41 of the block whenthe d iaphragm 37 is in the position shown in Fi 6. It is apparent thatthe diaphragm 37 ivides-the recess 23 into two chambers, the outerchamber 23 between the side wall 41 and the diaphragm 37 being always infull communication with a tracker bar tube 4 through the passage 22, andin restricted communication withthe recess 30 through the'vent 28. Theinner chamber 23 formed in the recess 23 is always in communication withthe atmosphere through a duct 42 provided by a circular saw cutextending from the bottom of the block as clearly shown in Fig. 3 andwhen the valve 35 is separated from its seat 35 as shown in Fig. 6 thecentral opening 32 is also opened to the atmosphere.

Referring now particularly to the operation of the several parts shownin Fig. 1, it is obvious that when the movable leaves 10' of thecxhausters 10. are moved downwardly air is exhausted from the wind chest9 to the reservoir 11, the vacuum thus created being locked againstatmospheric pressure by means of the'valve-14, all asdescribed in myaforesaidv original application Serial No. 204,873. The vacuum in thewind chest 9 is transmitted through the registering slots 15 and 31 tothe chamber or recess 30 of each unit and the vacuum is also transmittedthrough the commu nicating recesses 29, 29 to the vent 28. The vacuum ofthe vent 28 is transmitted to the outside of the diaphragm 37 by meansof the tube 24, so long as the opening in the traiike r bar 2 is coveredbythe note sheet, so that the diaphragm 37 will tend to hold the valve'35 open and the valve 36 closed due to the atmospheric pressureadmitted to the inside of the diaphragm 37 by meansoi the slot 42.

The above described condition of affairs 15 illustrated in Fig. 6 fromwhich it is apparent that atmospheric pressure entering the slot 4-2 andacting on the diaphragm 37 is the active force which tends to hold thevalve 35 away from its seat Whiie at the same time maintaining the valve36 in close engagement with the shoulder-32 thus keeping suction awayfrom the central opening i l 3th this Condition, air at atmosphericpressure ad mitted to'the interior of the power pouch by means of'theslot 26 leading from the cen tral'opening -32, sov that the pneumaticremains in an expanded condition as long as the tracker bar opening iscovered by the note sheet.

When, however, an opening in the tracker bar 2 is exposed, atmosphericpressure enters the corresponding tube 4: and passing through thechannel22, overcomes the limited vacuum maintained in this channel through thevent 28 and ad vi air at atmospheric pressure to the outer chamberportion 23" of the recess 23. The result is that 'air at atmosphericpressure is then acting on both sides of the diaphragm37 therebyneutralizing the force previously acting on the diaphragm 37 andimmediately causing thevalve disk to be drawn-away from its seat 32 bythe suction effect on the side of this valve exposed to the recess 30,as shown in Fig. 3. the valve 36 opens the valve 35 closes, thereoycutting off the central chamber 32 from the atmosphere and admittingsuction to the central chamber 32 and the slot 26 leading therefrom," ii The interior of the power pouch thus being enhausted, atmosphericpressure surrounding the pouch forces it to collapse with the resultthat a note is striick by the lever 16 carried, by, the outer leaf 16.The lever 16 extends "beneath the end of a wippen 43 as shown in Fig. 1,so that when the pneumatic collapses the free end of the lever 16 movesupwardly thus strikingthe note in the usual manner. t is obvious'thatthe action of the powerpneumatic is quick and positive owing to'thedirect connection of the lever 16 to the leaf 16 with no motion lost intransmitting the action. Furthermore it is apparent from Fig. 2 thateach striker unit 5 practically lines up with the corresponding note, sothat the levers 16 extend rearwardly from the single row of unitswithout interference, each lever16 permitting a small amount of lateralbending'to bring, it directly below the corresponding wippen 43.

As previously pointed out my improved striker.v unit is particularlycharacterized by itsvery quick action in striking a note in re sponse tothe uncovering of an opening in I the tracker bar 2. This very quickaction results to a large extent from the fact that the valve 36 whichcontrols the admission of suction to the central chamber 32 to collapsethe power pouch, opens in the direction of the induced flow of air. Thatis to say there is always, as long as the exhausters are operating, atendency to draw air out of the recess 30 and of course the vent 28always permits a limited amount of air to be exhausted from this recess30. But it is perfectly obvious that with the parts in the positionshown in Fig. 6 atmospheric pressure within the central chamber 32exerts a tendency to push the valve 36 away from its seat 32 to admitatmosphere to the recess 30. However this tendency for the valve 36 toopen is counteracted and overcome by the greater force exerted byatmosphere pressing on the under side of the other valve and on thediaphragm 37 itself. Obviously the combined areas of the valve 35 and ofthe diaphragm 37 exposed to atmosphere are much-greater than the area ofthe valve 36 exposed to atmosphere, and since there is a suction effecton the outside 01" the diaphragm 37, the forces tending to move thespindle 33 to the right are preponderantand suiiicientto hold the valve36 tightly closed on its seat 32. However, as soon as an opening in thetracker bar 2 is exposed to the atmosphere the rush of air atatmospheric pressure through the tube 4 almost instantaneously overcomesthe limited, although heretofore suilicient, vacuum effect in theoutside chamber 23 of the recess 23 and conditions within the unit areimmediately reversed in so tar as results on the valve 36 are concerned.As soon as atmosphere is admitted to the chamber 23, the forcepreviously exerted on the diaphragm 27 and valve 35 is eliminated sothere is a sudden and immediate pressure exerted on the inside of thevalve 36. As previously pointed out this opening pressure on the valve36 had been in existence before so that as soon as there isneutralization 01 the forces acting on the diaphragm 37, the valve 36starts to open and once started the movement is almost instantaneous dueto the rush oi air past the valve 36. In other words once the forcesacting on the diaphragm 37 are counterbalanced, there is no forcewhatsoever tending to hold the valve 36 closed and it opens in thedirection of the induced flow of air.

It should be particularly noted that the various ducts 26, 31 and 42 areshown as being made by the use of small circular saws of the properdiameter while the v rious recesses such as 23, 29, 29 and 29 are shown,

as being made by the use o1 boring tools oi the proper diameter. By thismanner of forming it is possible to produce standardized units properlyrecessed and slotted in very large quantities with relatively smallexpenditure of time and labor and with absolute accuracy. It is to beunderstood, howmy invention I have provide ever, that the principle ofmy improved pneumatic unit is not dependent upon the exact form of thevarious ducts and recesses which can be made in other ways than as shownto obtain the same results.

From the foregoing it is ap out that by F dn improved pneumatic strikerunit for player pianos that can be quickly and cheaply manufacturedoperates in" an extremely effective manner in striking a note. 7 Theunit is further characterized by its very compact form due in (part tothe manner of forming the slots an recesses and to the disposal of thevalves in vertical planes. This construction results in a very narrowunit which lends itself to the arrangement of all of the units in asingle row above the key board of the piano with each unit insubstantial alinement with the key, the note of which is controlled bythe striker unit. v

I claim,

1. In a valve action for striker pneumatics,

a diaphragm chamber, normally under exhaust, and covered by a diaphragm,a valve chamber and a valve mounted therein, said valve chamber beingnormally filled with air below atmospheric pressure, a passage be tweenthe valve chamber and diaphragm, means providing communication betweensaid passage and. the atmosphere, and means for providing communicationbetween said assage and the proper pneumatic, said rst named means beingclosed by movement of the diaphragm when atmospheric premure is admittedto the diaphragm chamber.

2. In a valve action for striker neumatics, a diaphragm chamber, adiaphragm covering said chamber, a valve chamber normally in anexhausted condition, a passage between the valve chamber and thediaphragm, a valve in the valve chamber and adapted to close one endof'said-passage, a second valve on the diaphragm and adapted to closethe other end of said passage, means providing communication betweensaid passage and the power pneumatic, and means placing the one side ofthe diaphragm constantly in communication with the atmosphere;

3. In a valve action for striker pneumatics,

a diaphragm having a chamber on each side thereof, a valve chamberspaced from the diaphragm, a valve in said chamber adapted to beoperated by the diaphragm, means connecting the chamber on one side ofthe diaphragm with a tracker bar, means providi communication betweenthe atmosphere an the chamber 011- the other side of said diaphragmmeans providing a passage between said last named chamber and the valvechamber, and means providin communication between said passage and t epower pneumatic,

with said valve chamber being constantly subject to exhaust tension,

- 4. In a pneumatic striker unit for musical a diaphragm, and therebyforming an open air chamber on one side, and grooved and recessed on theother side, to provide a v uum chamber and valve sod, a valve fortaaidseat, a vent to conduct alimi'ted flow of vac, uum on one side of thediaphragm and means for connecting this same side of the diaphragm tothe opening in the tracker bar, a port connecting the outside airchamber and the vacuum chamber havi a groove therefrom to the interior:5 the power pneumatic, an outside air valve on the diaphra for seatingagainst said port, and means or retaining the said valves in properrelations to their respective seats.

5. In a pneumatic striker unit for musical instruments, in combination,a block chamfered to present a surface to contact with one face of awind chest, and leaving a rtion to extend past said face of the wind 0est, said extended portion forming the fixed leaf of the powerpneumatic, a tube and channel inlaid extended portion to convey air fromthe tracker bar to the primary diaphragm in the said block, a groove andrecess provided on one side of the block to receive said diap and thusform an'atmospheric air chamber, a valve secured to said diaphragm, saidvalve cooperating with a valve seat and port leading to a vacuum chamberon the oppote side of said block, a valve in said vacuum chamber andoperatively secured to said diaphragm in said atmospheric chamber, avent in said vacuum chamber to conduct a limited amount of vaccum to oneside of said die hragm, whereby said diaphragm is forced y atmosphericpressure away from the said valve'seat in the atmospheric chamber, andat the some time draws the valve in the vacuum chamber tight against itsseat when the note is normally idle,-and whereby, when an opening isexposed in the tracker bar, atmospheric pressure will overcome the ventand both valves will move in the direction of the induced flow of air tostrike a. given note. I 6. Ina pneumatic striker unit for musicalinstruments, a block recessed to form a vacuum chamber and anatmospheric chamber grooves in said block to supply air to chambers, andports connecting said chambers together and both chambers with theinterior of the power pneumatic, a. (lia phragm and valve co-operatingwith the port in the atmospheric chambenand a valve cooperating with 5PMinxthe-vacnnm= t chamber, both valves being operatively connected withthe diaphragm, a vent-in the vacuum chamber for mind i a'limited supplyof vacuum to the-side of the diaphragm opposite the atmospheric chamberchamber closed, and when an opening is exposed in the tracker bar,allowing the valve in the vacuum chamber to open and the valve in theatmospheric chamber to close, thus causing the power pneumatic tocollapse.

7. An automatic mechanism for player pianos, comprising a collapsiblepower pneumatic, a tracker bar having air ports controlled by aperforated note sheet, a casing intermediate the power pneumatic and thetracker bar, subdivided to form a vacuum chamber communicating withsuction apparatus, and an open chamber communicating with theatmosphere, a power conduit connecting the interior of the powerpneumatic with both chambers, and co-operative means whereby, when atracker bar port is closed, the power pneumatic is connected with theopen chamber, and disconnected from the vacuum chamber, and when saidport is opened, the power pneumatic is disconnected from the openchamber, and connected with the vacuum chamber to cause an induced flowof air from the power pneumatic to the vacuum chamber, and the collapseof the power pneumatic by external atmospheric pressure, saidco-operative means including a valve and valve seat for controlling thepassage of air from said power conduit to the vacuum chamber, the saidvalve seat being between the valve and the power conduit whereby saidvalve, to open, moves in the direction of said induced flow of air, theentire mechanism for striking the note being contained in one unitarystructure.

8. In an automatic mechanism for player pianos, a vacuum chamber, apower pneumatic, a power pneumatic conduit, and means for bringing aboutthe induction of a flow of air through said conduit to the vacuumchamber to cause the collapse of the power pneumatic by externalatmospheric pressure, said means including a valve and valve seat forcontrolling the passage of air from said power pneumatic conduit to thevacuum chamber, the said valve seat being between the valve and thepower pneumatic conduit, whereby said valve, to open, moves in thedirection of the induced flow of air, the entire mechanism for strikingthe note being contained in one unitary structure.

WILLIAM B. TUNSTALL.

